Katie and Guy take a sea cruise in their sailboat and discover a couple on a wrecked boat, victims of a brutal attack by their crew. They take Eliza and Nick on board. The new boarders appear nervous about returning to Honolulu, and when the boat's engines die and other little incidents occur, Katie and Guy start wondering whether the shipwrecked couple are what they appear to be.

Facing his parent's impending divorce and emotional upheaval, a young boy runs away and joins a gang of London street urchins who live by their wits, begging, and thievery.

When villagers begin disappearing it is discovered that they had fallen through a crack in the earth which goes straight to Hades. Hercules once again comes to the rescue and faces one of his most difficult challenges, and must prove himself as a man as well as a god. "Hercules in the Underworld" is the fourth made for TV movie in the series Hercules: The Legendary Journeys.